The bakery chain Greggs has said it will increase the price of its breakfast deal and a number of other products this week after unusually hot weather hit sales over the summer. The group said its three-part offer, which includes breakfast roll or baguette, a hot drink, and a side, would rise in price from £3.95 to £4.15. Alex Smith of the research company Third Bridge said Greggs could no longer rely on sales volumes alone to absorb cost inflation. The move formed part of an average 4% price rise on key items including coffee and doughnuts. Greggs said it has opened 57 net new shops this year and expects about 120 net new openings by the end of the year.