Typical,come in at a low price thinking your doing someone a good turn while every other trade rip the arse out of it!!!!!! And they come after u !?! Sympathies bud. Suck it up and take a sparks or plumber course so u can rip people off legitimately
In my humble opinion mm and ultracolour both suck (literally) actively looking for substitute..pin holes, collapses in joint,and for the genius who suggested it's the grouter ,that false superiority complex could get you in trouble