It sounds like the mixing cartridge on the faucet will need replacing. Special tools may be needed depending on the brand of the cartridge, Terry

: It seems that we are getting cold water mixed in with our hot water. If I turn off the supply to the water heater, I still get cold water through the hot water taps. We also have a problem with cold showers, particularly in the afternoon, even though the water heater is turned up high and the water is hot. Could water pressure be a cause?
: Finally, I have tried to change the guts of the single handle valve in the shower and cannot get the outer sleeve out. The inner spool has come out by pooping the snap ring past the groove, but the outer sleeve is stuck even though it will turn. Any suggestions on how to get it out?