Require replacement battery pack and charger?

You didn't bother to tell us the maker but a quick Google search suggests these are Challenger sold through Argos.

Cheapo Chinese pile ';em high & sell 'em cheap with next to no support.

If you'd bothered to do a quick search for yourself, you'd have found results like these:

http://bit.ly/20DtPDZ

espares MAY be a goo dplace to start but I wouldn't indulge in breath holding.

Anon
May 2016