Question: Can Canada Pension or Old Age Security payments be garnished?
Answer: Under the Ontario Wages Act only wages can be garnisheed. The only exception would be if you owe money to the government, such as the Canada Revenue Agency, they can garnishee a CPP or OAS payment.
One option would be to simply open a new bank account at a new bank, and deposit your CPP and OAS payments there; since your other creditors do not know about that bank account, they cannot automatically take money out of it.
Another option would be to file a consumer proposal or bankruptcy to officially eliminate your debt. However, you are then making payments towards your debt to protect yourself from creditors who may not have any legal recourse against you, so you should consult a licensed Ontario bankruptcy trustee to determine if that approach is in your best interests.