Hey, I've got a Worcester Boiler, and when I try and turn on the shower I get nothing but cold water. But when I turn on the hot tap it's hot. I've also found that if I turn the shower on then switch the hot tap on for a few seconds, I get hot water into the shower for a few seconds until the boiler cuts out and I get cold water again.
Any help would be much appreciated, cheers.

After looking round I've noticed the hot water taps (which still work) have less pressure in them.

One more quick update. The shower is now working. But we're having trouble with the hot water pressure all round the house. I've found that downstairs the area near the stop cap is making a much louder sound than usual? Maybe if I turned it off then on, it will fix it?