I ask this as i have recently had a couple of instances as i'm sure many people have where i'm told something on the phone by a company only for it to be denied later on.
1st one was with my mobile provider-I rang to cancel my contract and was offered an iphone at a really good price. During the call i was told it included applecare protection but a price for this was never mentioned, which subsequently appeared on the bill. After a couple of phone calls i managed to get the charge refunded.
Previous to that i had power provider telling me i was due a refund only for it(and the call) to be denied later on. Another couple of calls and i managed to get that back too.
Yesterday i was talking to a guy from Sky about signing up, after a 20 minute call i said hold on a second just run through what exactly is included and the charges while i record the rest of the call. His 1st reply was i don't think you can record the call, asked him why not as at the start of the call i had a recorded message saying calls were recorded for training purposes, so they're allowed to. He then put me on hold while he spoke to a supervisor, eventually i was told it would be ok but guess what all of a sudden the free installation of a new phone line "might" have a charge!
So i am now thinking in the future to start recording all calls involving anything that may cause me hassle later on. I am quite prepared to tell them i'm recording the call, although i'd prefer not to as i think i could get a lot of freebies after providing recordings of promises made on the phone

Nick