what is wrong?

i have a 6 month old bosch classixx washing machine. It is washing clothes but not spinning, thus water is left in drum. I thought maybe the filter is blocked, but unfortunately i cannot unscrew cos of the build up of pressure. Customer care have said that i will get charged for an engineer to call,although machine is under warranty, if the filter is blocked, as apparently it has to be checked every month. Once the filter is seen as ok, then they will look at other problems, but how can i get the filter cover off?