Mobile data

Any recommendation on best deal for data + calls+sms for iphone? coming from countries where unlimited data, hours of calls and thousands of sms for low price are the norm , i find Belgium really backwards...I have a running contract here of 5€ a month on Mobistar, as i'm mostly absent but now that i intend to stay here over the summer am looking for a data + calls deal. i have bought a 'data everywhere' micro sim from Mobistar paid 15€ for 250mb and it lasted me barely 4 days! this is ludicrous!
Any advice? Ta