Customer service is nonexistent

Their customer service is nonexistent! They don’t care about us as customers. I sent them an email and no response. I was left with only 2 instalments but instead they took 3 and in 10 days they will be taking the 4th one. Where should we take our queries to if they are not willing to assist us because I’m not the only one who’s complaining about their poor customer service. They need to do better!