Is it worth fixing my aquatronic 2 shower? The temperature is very eratic?

I have an aquatronic 2 shower. Ever since I moved into the house in August, the shower has been temperamental. Sometimes the temperature is steady. The next time I shower it can suddenly get very hot and then cut out. If and when it comes back again it can be very cold and then hot again. I assume the thermostat is a bit dodgy.
I am looking to have my bathroom refitted completely in a year or so and am therefore only looking for a cheap make-do solution.