sales or percentage bonus on gems

Every game I have ever played on android will put there bought in game currency on sale or offer a percentage bonus on the packs, higher percentage on higher dollar value. I have been playing CoC for quite some time now and they never put out any sales or bonuses to there gem packs. I believe they should be doing that for there customers. I have spent plenty of money on CoC. Who else agrees with the fairness and need of occasional sales or percentage bonuses to the gem packs?