My water supply is via communal tank. Cold water pressure is fine in basin but low in the bath taps, so have had taps changed twice but problem still there - hot water pressure is fine but as the cold pressure is low the water gets too hot when taking shower. What do I need to do kindly advise. Thank you.

Hello Dossak, it is interesting question you are asking: it is usually the other way around...

Sometimes there is a kink in cold water pipe inhibiting water flow. Also, you may have a valve on cold water pipe that is 1/2 closed...

Moreover, check your stops on each tub /shower faucet. It may be 1/2 closed. Some faucets have filters at the stops. Make sure this filter is clean.

Lastly, you are not specifying brand and type of the tub/shower faucet in question . I would check hot water balancing adjustment on tub/shower faucet. Some faucets, like Grohe Temperature valves, have to be periodically re-adjusted for proper mixing balance...

Back to you... Milo