If I pay it all at once it will cost £159 and I won't need to pay it again for another year.
If I choose quarterly it will be £41 x 4 with a charge so in a years time I will have paid roughly the same give or take the extra charges.
However with the monthly option it is £26.50 for 6 months then £13.25 going forward. So this time next year I would have paid them nearly £80 more.
Am I missing something obvious?