i have a damp patch which is caused by rising damp from a deteriorated dpc, . it is about a half metre in length patch of damp. is it worth injecting the whole length of the wall (3.5m) or just a metre section where the dpc is breached? also how much will have to be replasterd on the interior wall, just where the damp is or all the wall length , or depends on wot length a new dpc is put in??