You can easily top up the prepaid credit for your e-plus mobile phone tariff on your mobile phone. All you need is a credit voucher and your mobile phone - the credit will then be credited to your account. You can find out exactly how this works in this guide.
How to top up your e-plus credit
Since e-plus was bought by the Telefonica Group in 2014 and since then the offered services have been somewhat restricted, the credit can only be topped up with e-plus via the service code or hotline on the mobile phone..