Post Office Ltd will not "Exchange" these notes. They can be accepted, as payment towards a bill or as a deposit into a Bank Account, but due to restrictions on Cash Holdings, Post Offices cannot exchange them. And I wouldn't attempt to just buy a stamp with one as again it'll probably be refused! I'm actually surprised by the banks agreeing to exchange them, as everything I've seen used the wording "Accept", not "Exchange" and in our neck of the woods they try and palm off to us! To be honest the only ones I know who will exchange are the Bank Of England.

From reading the thread and the OFT doc this companies T&C's are in breach of the law, and so are null and void. Think of it this way I could sell you a known faulty printer (to me, not known to you) make enough profit after postage and then refuse to refund your postage in the hope that you refuse to send it back, and so are in breach of your end and I don't have to refund you the original costs...