Can mains gas pressure make Combi Boilers run hot and cold water?

I've been hearing a lot about gas pressure being low in the news due to the excessive demand there has been on the National Grid during the recent long freeze..

Mine, and my in-laws combi boilers seem to have both developed a problem over the same last couple of weeks where hot water taps run hot and cold.

Could a drop in mains pressure create this kind of issue?

Or could there be a fault with our Boilers that makes them susceptible to this change?

thanks for any help in advance!

Lex L
January 2010