Cell c is exploiting customers

On 12th of February 2020 at 20:30 i received a message from Cell c telling me i have 1169 mb in WhatsApp bundles, 45 minutes later i get another message from Cell c telling me i have less than 722 mb in WhatsApp bundles. I called customer service and the lady tells me that i sent one message that cost 125mb and another one that costs 92mb . How is possible to use 447mb in 45?