Replacement Patchwork antenna

My Patchwork Go is not working properly as it keeps loosing signal and seems to have me driving all over
Tried up dating software to latest version but still no better, so spoke to patchwork and they said it seemed like the antenna was faulty, but as mine was an older antenna it is around £700 instead of the new style ones which are £75.
Has anyone any other ideas what might be wrong with it or a cheaper supplier of an antenna