Mtn taking double payments and charging for things which was returned advance

Good day worse experience having mtn they no help customers service even in store took double payments from me not returning my funds charging me for router which was handed in one month advance in store before contract ended closed still charging billing and yet fone gave them rms number states router given in mtn customer service all don't know what's going giving all different information cases numbers service terrible disappointed cause money was needed for my child education and don't care to solve over 2 weeks waiting no help at all from mtn