How can I fix my Bosch dishwasher exxcel/auto option?

My Bosch diswasher is malfunctioning. It is not cleaning the contents properly and the tablet is not always being released from the holder nor was it being wholly dissolved..
I was advised to leave the tablet on the floor of the machine which I did and it improved somewhat but problems continue:
the top rack especially remains dirty, eg cups have to be rewashed
the tablet is not fully dissolved
having run a further clean rinse, a froth remained
We have noticed that increasingly the machine is noisy in that there is a 'thumping' sound which relates to the water inlet, almost from the beginning of the cycle. This does appear to be increasing. The booklet does suggest it relates to the layout of the pipes but could this be contibuting to the problem?

I have cleaned the pump at the base and checked the inlet and outlet pipes and observed all loading instructions etc.
Is the machine not reaching a hot enough temperature?
In short, can you recommend any course of action to remedy this?
Incidentally I have checked in vain for the FD number and the ENR but it cannot be found! The only number is that on the back near the power cable inlet 5600041012/03/345/00.01

Kevin Yarrow
February 2008