A good option might be Sky Fibre who offer 40Mbps and 10Mbps upload, that way you're not paying full wack for an 80Mbps service that you would only see around 40Mbps on and you still get a nice upload. I doubt your line would go over 10Mbps upload anyway.
It's currently free for 6 months then £20 a month.
This being said TalkTalk is likely to be cheaper than most of the options out there and I am sure they can resolve an issue this small. I would be surprised if not! So I personally think it's best to hang in with TT I am sure they can over ride the computer refusing you.