Promotion percentage gets changed

[tonemanguitar1]

Has any else had their promotion percentage changed to a higher rate?  I have had several percentages increased and I did not make the change. It has to be done by eBay. In some instances the percentage was more than doubled.  A high rate that is not acceptable in my sales product category.  My 2nd part to this is anyone else finding that the percentage promo does not make any difference in sales or even ranking of any item. 

[ebooksdiva]

 Do you promote with fixed ad rate or dynamic? If you’re using dynamic that could be the reason your promoted rate is changing. I promote with fixed rate and never see it change. 
Choose your ad rate strategy - Dynamic ad rates are applied by default. If you want to change your strategy, here are your options:

• Apply dynamic ad rates: The dynamic ad rate strategy automatically aligns an item's ad rate with eBay's daily suggested ad rate. With this strategy, you do not need to make daily, manual updates to keep your listings competitive in the marketplace
• Set an ad rate cap: Set the maximum ad rate you’d be willing to pay. Your ad rate will never exceed this amount