I think DTI can assume jurisdiction over your complaint. The one who advised you otherwise may be mistaken. I have checked with DTI”s website and it would appear that your complaint will fall on manufactured products (office machine) and it is stated that:
“For complaint(s) on manufactured products (appliances, cars, furniture, office machines, laundry soaps, detergent bars, school supplies, processed milk, coffee, salt, etc.), call the Department of Trade and Industry at tel. nos.: 751.3330; 811.8231 to 33 local 1229; 751.3236; and 751.0384 locals 2223 and 2225.”
Please see: http://www.dti.gov.ph/dti/index.php?p=135&c=38&pg=2
Try calling the above contact numbers to assist you with your problem.
I sympathize with your problem especially because you are just operating a small business. Your concern that Canon might file a case against you is very likely to happen because you have issued checks in its favor. In all likelihood, Canon will file criminal case/s for violation of B.P. 22 (“Bouncing Checks law”). The problem with a criminal case for B.P. 22 is that good faith is not a defense. What is punished by law is the mere issuance of a worthless check.
If you have issued 12 worthless checks, then Canon can file 12 counts of violation of B.P. 22.
Of course, absence of consideration is also a defense in B.P. 22. For example, you issued a check to purchase a printer and the seller was not able to deliver the printer. Subsequently, your check bounced. You have a good defense in case the seller files a case for violation of B.P.22 because of lack of consideration.
The problem with your situation is that Canon was able to deliver the printer and you in fact accepted the same. It also appears that the printer is in good condition and the only problem is that it is not suitable for your business. Under the circumstances, it cannot be said that your checks were issued without consideration.
Also, try communicating further with Canon. You can try negotiating for the replacement of the printer with another that will suit your business needs.