Ariston Dishwasher LSV 67 AIX wont fill with water...

Question

Hi team the subject dishwasher has a two part filter assembly "A" coarse & "B" fine. The user manual states that the "A" is to be cleaned after each wash & "B" monthly. When the machine failed to fill I checked both filters, they were OK. I poured water into the machine in case it had a dry sump, it pumped out & still did not fill. I used the manual check list without any change. I then cut the power & water then contacted a repairman. A few days later he arived he went directly to the filters then scraped a filmy residue using his thumb from the "B" filter . He then turned on the power & water & the machine ran ok. He advised that the problem was a "messy/blocked" filter & that scraping it with his thumb had solved the problem. We were charged as a "blockage" is not covered under our extended warranty. Aprox four days later the machine again failed to fill with water. I tried the "thumb" treatment on the "B" filter even though I dont agree with the "blocked" filter contention. However I cant get the machine to fill. I have been told that if a service man attends again & he records the filter as "messy/blocked" I will need to pay again. I am confused as we have had this machine for 5 years & have always cleaned the both filters.
Help
Robert