Can not keep to a commitment

We went to vodacom cape gate (opposite checkers) to take out a new contract for a tablet. The lady that helped us ( Rushda) said they did not have stock of the one we were looking for but she will have one for us on the latest wednesday. Thursday evening we went to them and there was no stock. Another salesperson phoned all the branches and they also did not have stock. I feel they should have let us know they could not source us with the product. This is the third time in less than 6 months that almost the same problem has risen at said branch.