We have a Belling C Range 100GT all gas cooker. We used the right hand side oven to cook dinner an hour ago and when finished, were unable to turn the gas right off. The valve appears to be jammed, about a quarter turn from the fully off position. We have tried gently to shift it but it won't budge. A friend who is a registered gas installer has had to disconnect the main gas feed to turn the oven off so as it stands, we can't use the cooker at all. All was fine until a hour ago. can you help please? Thank you Model # 444440222 Serial # 30457463

Kitchen Ranges - Belling