Double charges

Why am I being charged double on my purchases, example did purchase then $30.99 I got my purchase but was also charged a 2nd amount of $30.99 that gave me nothing, impossible to find help questioning this online.

has happened a few times now, in past never had issues, just last month or so every purchase I get charged double.

in this case it’s for a coin purchase on Pokémon go, I’d be ok sort of with it if at least I got double the coins for being charged double the purchase.

i did contact Pokémon support about 3 weeks back, they tell me not there problem and contact apple, well apple dam impossible to contact seems.

so either I just accept it and know any purchases I do now I will be double charged for a single purchase, or just give up purchasing extras.

regards robert