You mean you had €20 cash credit and now it's gone?
Do you have membership auto renewal enabled?
Automatic membership renewal
If so then perhaps the credit was used to pay for an automatic membership renewal?
What does your My History page say about recent payments/purchases?
http://www.48months.ie/my-48/my-history
Have you used any services that would have been charged to your cash credit balance - e.g. international calls/texts, MMS, special national landline calls (e.g. 1850, 1890 etc.)?
Hope this helps.
