DHCP WAN with ISP MAC Filter

Hi.

I have MikroTik RB951Ui-2Hnd router. My ISP provide me DHCP WAN. My old router mac registered by ISP. I tryed config mikrotik. Mikrotik obtain ip adress. Bu i cant acces internet.
I know reason, mac filter by isp. When i change ether1 mac with registered mac, mikrotik cant obtain ip automatic.
I call isp, they require me i pay support money. But i dont wanna pay to them.
Sorry my bad English. Please help me.