Unhappy in this contract

I took a contract with Mondo in April 2022. I was sold a router (that I can carry in my bag and use wherever I am - only to realize this router works only when it is powered to electricity) that will give me 150GB per month and if I don't use all of that data, this month data will be carried over to the next month. Only in December I discovered that something did not add up. I had visitors for a week and to my surprise, my data finished. When I enquired, I was given a 3months no payment as an apology but this issue was not sorted because on the 15th of August I was out of data again. When I called, I found that I am only left with YouTube data and night data. Now, I paid a close look to this account this morning from the app and on the 17th I get data top up. To my surprise - I have 89.39 GB remaining. Broken down I have fixed lte inclusive of 30GB. Promotional data of 30GB. MTN night promo data 50GB. Night express inclusive data of 30GB. When I add all these broken datas, I get 150 and coming to the 17th of the month and I have 89GB of data on day one does not make sense. I need assistance because when I call MTN customer service I get no help and Mondo is sending me back to MTN. Please assist.