Lying on legal documents to force their hand for bigger monthly installment

I have been paying my account without fail every month. Today I receive a letter stating that Groenewald Lubbe will proceed with legal action because I haven't made payment in the last 20 days. This is a blatant lie on their part, when I phoned their offices, the lady I spoke to confirmed that they received the payment I made on 1 April. I got transferred to another lady who apparently deals with my account who informed me that they want to proceed with legal action because I cant increase my monthly amount. They called me a while ago asking if I can increase my amount, and I indicated to them that I am not able to increase the amount, this cant be a valid reason to take legal action, seeing that I am still making payment. And to then lie about the reason why the want to take legal action?