Thank you for your post and the extra information.
It does sound like you have exceeded the maximum voltage input and this has probably damaged the unit. If you wish to return the unit to us then there will be a charge of £50 plus tax and delivery for the repair. If the unit is beyond economical repair then we will contact you to discuss further options.
In order to return the unit to us you will first need a returns number. Please do not send us the unit without first obtaining this number. To obtain a returns number please email us the following information:
Unit being returned
A brief summary of the problem
Please email this information to firstname.lastname@example.org