Can anyone help answer my question, which i hope is a simple one but cannot find an answer!

Having recieved my copy of my loan agrrement from 2/4/2007, the amount of the final repament and dates due are completely wrong.

I have spoken to HSBCicon who have acknowledged their mistake and agreed to put this in writing.

My question is this: does the fact that the prescribed terms are incorrect make the agreement unenforceable? in the same way it would if they were missing or does the law only apply to MISSING prescribed terms?

Either way what should my next move be upon reciept of their letter?

all advice very much appreciated