Ask for how to catch Chase's rebate for Exxonmobile mastercard?

I get Exxonmobil master card for two years ago and my lifetime Rebate balance $216.54 but I did now how to take my rebate money from them, I call to Exxon credit service they answer I just bring my statement to gas station show my balance I had and they will be help me, but this morning I did it ,but the Gas Exxon from Phoenixville 's Gas Station He did not know ,and he direction for me : I need go to the web WWW.mastercard.com/exxonmobil .I did aldready ,but not worked ..so please help me