hi it looks like some of the seams on my overcoat are letting water through. what glue would you recommend to fix that? its 100% polystyrene, thanks
I doubt its polystyrene, 100% polyester is the norm and the seams are usually welded. Buy a new one 
lol - autocorrect yes it 100% polyester, no l dont wanna new one ;( bought it last season, prefer to rescue it;)
Unusual for the seams to go unless under stress, faulty workmanship or do you need a larger size?
Glue will not withstand the rigours of over suit life, if repairing it needs to be welded.
This stuff
https://www.mcnett.com/gearaid/tenacious-tape#10691
Is about £5 from camping shops or Amazon
I would use stormsure glue for seams (I think they do tape too but I’ve never tried it)
duct tape.
good stuff , thanks
What do I know, Stormsure may be your friend
I use stormsure to hold my ever-increasing gut inside my ever-diminishing wetsuit. The stormsure never fails - but the neoprene around it continues to split and I chase it with more stormsure. Soon I will have a suit of stormsure and I’ll be able to bounce along on my arse - it’s a bit like flubber (stormsure, that is, not my arse).
Wow! Hadn’t heard of Stormsure before.
Unless you go diving or do other water sports then that is not surprising.