Topaz 2000 leak

Hello, this is my first post,
Can anyone help I have a Topaz year 2000 and I have found water getting in in the right corner of the shelf above the bench seat. When I bought it I noticed a previous stain but thought it had been resolved as the shelf was completely dry.
But after owning for 18 months the shelf what’s become wet just in the corner driver side. I thought it maybe coming in from the outside channel above the window before the roof join. 
Can anyone suggest anything that might be easier to resolve? It’s going to a garage on Monday4th November 2019 
TIA

I had this on my Topaz, this year, had mobile fitter , he took out the top windows, cleaned them up and the surround and resealed, only way to do it, just resealing doesn`t work, After all the heavy rain recently, still bone dry.

As I found out from a previous mobile MH service engineer, she just squirted sealant around the window.  So best to go on recommendations, just because they are accredited doesn`t mean they are all good.

To get the stains off, spray with stain remover, I used Aldi`s,  leave for a few minutes, then dab with water on a kitchen roll tissue, several times, do not over wet, after rinsing leave to dry, all stains gone.works a treat. this time of year would be better with a bit of heat in the van, I keep an oil radiator in there. will soon dry then.

Best regards,
Margaret

Most likely from the window seal,  A known problem with these top windows.

Oi Thank you for your reply I will see what the garage guy says on Monday. If you don’t mind answering c what sort of price would I be looking at?

The first one charged me £60 for the two windows, that was just putting sealant round, didn`t work.  the second one must have been over £100 he was here for 3 hours and did a really good job.

When you said it is going to the garage, does he do MH repairs then?  my mechanic wouldn`t do that anything mechanical on the base vehicle yes.