Gas problems?

we have a touring caravan which we heat with the blue bottled gas but over Easter we found that the fire was burning really low and the gas flames for the cooker where very low too...we managed to make them higher by shaking the gas bottle could it be that we need to change to the red bottle gas, it was quite cold, or do you think it could be something more serious? we need to know asap as we've still got a few weeks of warranty left... thanks