B&M - got a call last week from a lady about the letter I sent in complaining about the 'faff' along with the cheque requested to get the linked account changed back to the original one.
She confirmed that there was not a need to send a cheque every time a linked account was altered so will make sure the lady I spoke to originally is informed so she doesn't give out the wrong advice in the future, the only time this should happen is if the account being switched to is newly opened as it may not be in the 'system' fully in order for the automatic checks to be carried out which I appreciate, but that wasn't the case with mine.
She did also say that not having any message on the screen when my accounts 'disappeared' to say why and/or to contact them about it, was very bad policy and she was therefore referring this upwards to get it resolved.
The best bit is though, due to the aggro I was given £25 in compensation! Not something I expected so a very nice surprise and will pay for new Three phone contract that I signed up for as a pressie for my Mum last week.