Had a new response to this (below) which isn't much cop to be honest. Looks like I'll be looking for somewhere new or scrapping my ticket altogether:
This is caused by a natural spring which is underneath the stadium but due to the depth of it, is not something we are able to reach. The reason it comes through the concrete is down to the water pressure which creates cracks in the concrete. Due to what it is, there isn't a way we can rectify this, as it would just force the water to come up somewhere else.
They also said I had to get in contact again on renewals day to see what they could find for me. It's a load of shite the customer services team, they should really be contacting me with the options (once they know them) rather than me having to chase. Clearly too much to ask though...