Good Morning Martin,
Was the replacement pump a main dealer or aftermarket item?
I only ask this question because I had the same issues with my S7 and the independent garage I took it to gave me the option of both, but did explain that aftermarket pumps can give up quite soon - maybe 12 months or possibly sooner after fitting depending on make
As a consequence I opted for the main dealer pump and yes it was dearer, but not by a huge amount and its still working!
Best of luck sorting it
Chris