Two cap increases in six weeks, thanks!

I received a letter about six weeks ago from Vodafone saying that my 200GB plan would increase to 250GB at no extra costs from March 1.  I looked at my usage meter today to check this had happened and saw that my allowance was actually 500GB, I thought this was a mistake until I saw my bill which had a note saying that my allowance had increased from 250GB to 500GB at no extra cost.  It was never 250Gb but thanks Vodafone.

I'll be hard pressed to get through that but i will give it a crack!