Hi I wonder if anyone can help

I have an A5 sline TDI 2.0 litre and recently the windscreen washers stopped working so I thought a fuse but nope then bought a new pump and it worked a day later stopped thought faulty pump bought another changed bad it worked for a day again ......

Checked fuse perfect and I got an electrical tester that shows power at the fuse and pump but it is working then not then working any help appreciated

Thank you