COMPLAINTS AGAINST A CONTRACTOR - PLS HELP

Good Day Everyone.
I have a problem with my contractor. Only recently I found out that they dont have a PCAB license.
Around October 2013, we hired them to do some finishing works of our Second Floor interior (plastering, tile works, paint, electrical). It was a Phase by phase contract and payment was made partially, and we still have around 30% balance due. But I decided to hold the payment because we found out that some materials were missing/uninstalled, and super overpriced. For example, they charged us 50pcs junction box, but on actual counting they only installed 23pcs..also in the contract they provided around 900pcs tiles but only around 400pcs were installed..and still more missing.
With regards to the price, for example: market price of Tile Grout is only P47.00/pack, 1pack Tile grout contains 2kilos..they charged us P1,250.00/kilo tile grout, and in other pages is P150.00/kilo.
I asked some licensed Engineers about their opinion on this and all of them told us that this contractor doesnt know how to make a decent quotation.
Now my problem is, I didnt know that they have to provide a so called blue print? Also, they dont have a PCAB license and their contract with us is Null and Void.
And they are forcing/harassing us to pay the balance and telling us that they dont want to finish the job anymore because they are upset because I did some market price research on all materials. they are upset because we questioned their contract.
Anyone pls help me assess my problem, some transactions are verbal but we have real evidence of the issue.
Now I want to know if we have the right to sue them and what would be the status of our case?
Pls anyone help..
Thank you so much.

Gerann:

with respect to your concern:

1. How come it is only now that the non-PCAB requirement was discovered after the award of the contract to the concerned contractor?

2. Coming from you, there are discrepancies in the supplies delivered as to quantity or maybe quality, now resolution of the problem depends on the existing contract between you and contractor.

3. The contract is already executed to the point that works started way back October, 2013. There is now performance of an obligation to to do, though, through discovery there are materials of inferior quality was used, as alleged. Lession/damage might have seeped in.

3. Does the contract contain the posting of a performance bond which is usual and normal in contract to build or to do?

4. Proper resolution of the problem requires a contract-review prior to any future action.

5. Payment could be held in abeyance to the contractor (depending if the contractor agrees) otherwise, breach of contract would be an incipient action.

If you need to discuss further with me... pm me

I might be of assistance.

K.R.

Gerann:

R.A. 4566 as amended by P.D. No. 1746 provides that no contractor (including sub-contractor and specialty contractor) shall engage in the business of contracting without first having secured a PCAB license to conduct business. It is an offense to engage in contracting business without a license first being obtained. All architects and engineers preparing plans and specifications for work to be contracted in the Philippines shall stipulate in their invitation to bidders, whether a resident of the Philippines or not, and in their specifications that it will be necessary for any bidder, whether contractor, sub-contractor or specialty contractor, to have a license before his bid is considered. The purpose of the Contractors License Law (R.A. 4566) is to ensure, for the safety of the public, that only qualified and reliable contractors are allowed to undertake construction in the country. The law also aims to promote for the benefit of the public and private sectors and for the national interest, the orderly growth of the contracting sector and the upgrading of construction capability.