Purchase not loading because of 'account error'

Mojang,

About a week ago i purchased a Frozen 2 pack. Yesterday when I went to open it, there was an 'account error' which said if it lasts more than one day then to contact you which I am doing now. 

I am very disappointed with the service and I want you to fix it or give a full refund of £7.99. Please get back to me today or I will make another report. 

Many thanks, Lola