I am still receiving SMS for the "data volume is used up" from the previous (old) contract

Hi there,

A few months ago I switched contract. 
From contract X (that contained 100GB/month), to a new contract Y (than contains 200GB/month), those are example numbers.

Before the end of the billed month, after using more than 80% of available data, I’m receiving an SMS telling me that I used 80% of available data (which makes sense).
However, for some reason, I am receiving now SMS for both contracts, old and new:
- for the old Contract X (that contains 100GB/month)
- for the new Contract Y (that contains 200GB/month)

Quite annoying and confusing to receive both of SMS-es.
Even more confusing is the fact that those SMS are arriving for the old contract even 2-3 days after the billing month took place.


Does anyone experience something similar, and perhaps there is someone who can help me in solving that ?

Thanks