Aqualisa Digital Shower Filters?

We have moved into a house which has the Aqualisa Digital pumped shower and have just started having some problems with it. Frequently, we turn the shower on and the pump simply tries to pull water through but can't and therefore turns itself off. I cannot find any information online about what could be causing this, but thought there might be something stuck in the filters. Can anyone advise on how to open these up and check them?

I would call Aqualisa out, but we don't have any idea when the unit was installed and therefore whether it still under guarantee. Its going to be a final option.
thanks