they dont give you full trade if you havent been in regularly enough, therefore they may have put your prices up mate. Many other tile merchants dont do this such as Tile Giant and CTD to name a few.
Perhaps take your custom elswhere, Topps have good products available to buy but they need to learn that their way of trading with tradesman leaves many of us upset and in my opinion need to change.
i've used topps for quite a few years now never had any problems, although i do agree they can be a bit pricey with certain things. as of the bal adhesives, i bought some stuff this week and the prices have been the same as before