Charged R750 call out fee for changing AAA batteries

Ideal prepaid demand R750 for changing unit AAA batteries. I use prepaid electricity via idealprepaid. I kept on telling them that the rechargeable batteries of AAA alkaline of their brand is difficult to find. I asked if they can send them or direct me to a store where to buy. I bought AAA alkaline rechargeable batterries only to find that they don't work. I asked ideal prepaid for help since every time I ran out of electricity I must plug the unit at the neighbour for me to recharge. They said they will send a person to help but did not tell me how much the will charge. After the person installed R32 batteries I got an email from installation saying I must pay R750 call out fee. The argument started there. I normally budget R500 electricity a month. A normal doctor charges almost R500 consultation. Their call outfee is super inflated especially since they only changed batteries. When I disputed this with ideal prepaid, the lady claimed next time I buy electricity they will deduct the monies until I pay it. Hello Peter can you help me with this ******* of a call out fee?