should I take it back?

I just bought an old SLR Canon FTb camera with a 50mm 1.4 lens, hood and filter on it. It was cheap enough and I bought it thinking the lens might be really sharp and ok to use manually on my 7D.
Now I've looked on the internet I dont think it's compatible. I'm also concerned about fungus, I cant see any but it's very old and a little bit grotty. I can take it back and get my money back if I want. My other option was to send it off for professional cleaning but I'm not sure how much that would cost and how thorough it would be. Should I just take it back to the shop? Help!

Take it back. You're clearly not happy with it so do it before you can't anymore and regret it.

Take it back, save up and buy a new lens instead... or buy it used from a place you can trust

I emailed Canon to ask about having it cleaned. They wrote back saying they no longer have spare parts for it and it would cost more to clean than it cost to buy. If I wasn't worried it had fungus I'd probably keep it for fun and shoot some film every now and then, cause it does still work, I've tried it out. Also, if I had loads of shelf space I'd be happy enough to just let it sit there looking interesting, but back it goes today.