Gas Hob ignition fault?

Same problem as Ali, on a Bosch Hob, the rubber button cover split some time ago and was relaced with a perfume cap held on with a bit of blu tak! which has worked fine for 12 months. Now ignigtor stays on occasionally speeds up slows down goes off....! We also switch of when not in use. Have now disconnected the power as it was so annoying and use a hand ignightor bought for £5. Anyone found a better fix?