Canadian Tire (Moose Jaw)

I bought a bike with customer assistance and did not discover that pre-assembled bikes are non-returnable until after the transaction was completed.
On August 31st I bought a $109.99 bike at Canadian Tire ($215.30 with taxes and accessories). I'm a senior and just wanted to ride a bike for exercise. The sales representative I had asked for assistance, explained the differences among bikes and said the Superbike SC1800 is probably all I would need but the seat was uncomfortable. She directed me to the type she uses on her bike and I asked for help buying a lock and a helmet. I did not realize that bike was not the right size for me and she did not tell me to be sure I was choosing the right bike because it was a final sale, not returnable or exchangeable. At checkout I was given the warranty document but there was no mention that the sale was final. I tried to ride the bike at home and discovered that it was just too small for me, tried to adjust the handle bars and discovered that it was not adjustable. On September 8th I took the receipt to Canadian Tire, explained the problem and the manager said to bring it back and they would exchange it for a suitable model. Today, September 11th, I took the bike back and a different manager would not accept the bike pointing to the sales receipt which states that pre-assembled bikes are non-returnable nor exchangeable. I believe that at some point during the process of buying the bike I should have been made aware of their company policy regarding returns / exchanges of bikes. Simply printing it on the receipt after the transaction has been completed is not good business practice. Nor is it acceptable for one manager to tell me I could exchange the bike for a suitable one and pay the difference only to have me take the bike back and have another manager reject the exchange.