As I live in Poole I obviously use AL. It is my understanding that following the first two years of dealer servicing, to comply with Hymers warranty T's & C's, you only need to have the water ingress check performed by an authorised dealer for the following 4 years. Servicing can be done by a third party following the initial two years. Furthermore, it is my understanding that while the van is on the lift they examine the condition of the underside sealant and if necessary will reseal any damaged part. This year as out van is not being used all that's being done is the damp check to comply with the water ingress warranty. That check is being made 5 months past the anniversary date of purchase which is 9th April as a 6 month grace period is permitted within the warranty period. Obviously the last check must be done on or before the 6th anniversary which means there will be two water ingress checks in a year. The water ingress warranty has to be done by a dealer as all records are now held on computer at Hymer in Bad Waldsee and only a dealer has access to that system to update records. That's my understanding. Of course I may be wrong.