Vaillant Turbomax plus Hot water problems.MOV

The customer has got his boiler moved.. Since then the boiler is working fine for heating but hot water comes luke worm. Also.. sometimes when the hot water tap is on.. boiler is not coming on at all. Sometimes it comes on but continues on for considerable amount of time even when the hot water tap is closed. ( Heating demand was off) It seems to be more than one problem hear. Okey did they do the hot & cold water pipe work properly? Is it mixed or crossed? ....Next question is.. hey did they block the plate heat exchanger?.. or is it a problem with the PCB, Flow senser? or Hotwater NTC..? Well why did it go wrong when the boiler is just moved..I dont beleve in co insidents..What was faulty? I will give you a clue.. the boiler was repaired the next day because I did not have the part..(which was invented by Mr Hole who died without patenting his precious invention.... so .. poorly)