I am looking for support from you clever people.
We have had upstairs bathroom updated (3 beds semi, so it is the only washing facility really, downstairs is a tiny clock room). Original layout was bathroom and toilet separated as two small rooms next to each other, a shower over the bathtub. Original water outlet over the basin were two taps with hot and cold water. Water were running fine before the work carried out.
Work involved knock the wall between, removed bath. Replaced with new shower with shower screens, toilet and basin. plastering and shower panels rather than tiles.
Work took about 2.5 weeks.
Whole room looks fine, shower fine, toilet is ok with adjustment by the builder.
However the water run from the basin tap is weak with cold water, especially with hot water which is like a weak wee stream and took ages to get only warm.
The builder/plumber said it is because the original set up system which has nothing to do with them. He is saying that because the hot water tank is on the same level as the bathroom, so the pressure is very low that not enough to encourage the hot water to come out. He suggests to get a pump for it, but that is not part of this job?
I know the original system setting might be different as it is a 70s build house, but I feel difficult to understand that he is saying I pay him 6500 pounds, then when the water is not working properly, he is washing his hands off. He said his job as doing the bathroom is completed.
What should I do with it, please help, thank you everyone.