EXTRAORDINARY DELAY

Last Feb 2016, I and my contractor have agreed on the specific works to be done on my newly acquired condo unit for a specific sum. Most of the works stated on the proposal have been completed, except for some items i.e shower enclosure etc. The problem arisen when his supposedly 3rd party contractor for the shower enclosure did not fulfill his obligation. I, as the unit owner, has suffered due to this. It had been several weeks already since he committed to me verbally to complete the project despite what happened, however, until now I have yet to hear a word from him and the last time I sent him a message he has not answered any of my messages. I humbly ask for some legal advice on these questions:
1. Is the proposal valid and can be considered as a contract between us? (It's a signed document by us)
2. Can I compel him to complete the project thru any legal means?
3. What other legal remedies is available at my disposal?
Thank you very much!

if you are not yet fully paid, then it may be better to just get another contractor.

there is a contract between you because there is an agreement to provide a service. The document is proof of it.

if you want to compel him to do it, send a demand letter, then later you will have to go to court to demand that he fulfills his obligation