Following on from XRaySpeX, the TT guy is probably talking guff.
X seems not to have spotted what you said about the extra cost involved in th faster speed. If TT have LLU'ed it and samknows not caught up, there would be nothing extra to pay over their normal low prices.
If the exchange has however recently been upgraded to WBC, (BT Wholesale ADSL2+) then you could perhaps get 14Mbps, but at the extra price I suggest many other ISPs could do the same at a competitive price. If it hasn't, then 8Mbps is the maximum possible, as you say.
More importantly, the TalkTalk non-LLU service has a terrible reputation.
I suggest you put your number into
the IDNet checker and see what it offers. I say the IDNet one not as a particular recommendation, though they are good, but because they are one of the few ISPs that have a different range of packages for the BTW "up to" 8Mbps and 24Mbps services, so we get a reasonable indication of whether or not the exchange has been upgraded.
My broadband basic info/help site - www.robertos.me.uk
My domains,website and mail hosting - Tsohost.
Internet connection - IDNet Home Starter Fibre.
Live BQM.
"Where talent is a dwarf, self-esteem is a giant." - Jean-Antoine Petit-Senn.