As above, Halfords do a spray glue for these types of jobs, I've used it on seat foam that's split, but tape up the surrounding areas well as it can be messy & it's a shxt to remove on non required areas, so protect everything well, offer it up 1st as it may have stretched & if you start one end you may end up with an annoying fold the other, so best to see if starting centrally is best or 1 side to avoid any raised areas.