Bosch Aqua Stop Slimline Dishwasher not emptying

Hello all, having many problems trying to get my dishwasher to empty.

Had an engineer out who found many pieces of debris by the pump which he promptly removed and with much waggling of the outlet pipe got it emptying and it worked for approx a fortnight and has now stopped working again :0((

I have had it out and tried emptying it as he did and I cannot find any debris and the outlet pipe is completely clear as I blew through it and air is going into the water remaining inside.

The pump is working as its washing normally.

I read another listing sounding similar to mine which mentioned some matrix thing (have looked all over machine without understanding where this might be to clean out any residual sludge)???

Please help as this is driving me crazy and I cant afford another engineer!!!

If anyone needs the model number please advse me where I may find this ;0)

Many thanks for any help