An aircraft engineering company for which I do some work has, for many years, assisted pilots by offering them use of its fax to submit flight plans. Until afpex was introduced these were faxed to Heathrow FBU who were extremely helpful both in processing flight plans and resolving any difficulties. When Swanwick took over the task from Heathrow FBU the FPLs were faxed to the new number. One day the company received a most irate telephone call from a gentleman supervisor at the 'Help Desk' informing us in no uncertain terms that we may not fax FPLs because we 'have an afpex account' and must use that. This was news to us so we asked how FPLs should be submitted. We were rudely informed that they should be input directly to afpex. On investigation it transpired that when BT withdrew the Telex facility we were connected to afpex to enable continued receipt of incoming FPLs. This afpex connection cannot be conveniently switched to enable submission of FPLs. nats have been most unhelpful so we are no further forward. When the aircraft are collected the pilots are forced to seek alternative methods of filing eg. via expensive agencies. Maybe it is just one individual at the 'Help Desk' but such rude unhelpfulness is simply poor customer service from nats and reflects badly upon them.