I will divide my suggestions in multiple sections.
Paypal
If currently there isn't any payment method via paypal on the website, that must mean it's hard to implement, or low interest. But in this current state of the world, and the server, it should be thought about implementing.
Let's say the average age of a PandaWoW player goes from 15 to 30. Getting a hold of a credit card (VISA/MasterCard) is way harder than obtaining your countries debit card and sending money to your paypal, and do purchases.
The current donation methods are 1, via SMS, which most people wanna pay their bills separately from their online purchases, so they don't get involved with this method, except if they have no other way of donating, and 2 Paymentwall which includes credit card / more SMS methods.
Linking your own countries debit card (which are useless for worldwide purchases, but people have them because of their advantages in their cities) to your Paypal gives you a huge accessibility to every online purchaseable product. Fast and secure.
TL;DR Implement Paypal as one of your payment methods to increase donations.
Second suggestion which will increase the donations
Reduce.the.costs.of.bonuses.
Paying 50 euros for ~2500 bonuses in a PRIVATE server. Who does that.
Because of this people prefer buying in game characters for real money, because it costs them less. And PandaWoW gets no profit of it. Okay, it is bannable, a lot of people got banned for it. More than half of them get themselves unbanned instantly with their huge stack of bonuses they acquired via longtime character selling. But people who got caught selling/buying characters for money, aren't even 10% of the entirety of the community that do it.
Why?
Example : There is a decent character that can be sold for 6000 bonuses. 6k = 100$. Would you donate 100$ for bonuses and buy it in-game, or offer to paypal the guy 50$ for the character? This considering, receiving real life currency for your character interest people more than bonuses.
If PandaWoW wants to rise once again and have the same player base in early 2015-16, you should reduce the cost of bonuses to half. 6000 bonuses for 50$. So you get a huge profit and high demand on donations. (Example : a chocolate bar costing 5$. if 10 people buy it, the total earned for the company will be 50$. If you reduce the price of the chocolate, let's say 1$, way more people will buy it and the total earned for the company will drastically increase)
I hope this thread gets taken into consideration seriously, and the current stated so called "problems" get changed.
Thanks for your time, have a great afternoon.