MTN expires valid data and uses my airtime instead

Hi,<br> <br> Over the last couple of months, MTN has been putting an expiry date on the data I receive from a top up deal I've been on for years. <br> <br> They show that I still have data available, and yet my airtime gets used instead of my data. <br> <br> I've ended up using 100s of rands instead of my data.<br> <br> It would be great if they could stop putting an expiry date onto my data, and refund me for money I've lost.<br> <br> Please help.<br> <br> Kind regards,<br> David