Share 'maintaining polytunnels'

I have a tunnel thats about 20 years old and the plastic is ripping along a horizontal seam, its about 3 metres long now and i'm in a muddle about what to do...fix it?  tape up all the holes, rips, strimmer damage, bamboo cane stabbings, earth up the wavering sides to get it taut again or just give up and buy another thermic polythene covering...oh dear...why can't I just make a decision and stic…