If you insist on MAC filtering you'll discover this issue on many routers. This is why I don't use that and use a simple router defaults and then change the SSID and then WPA2+AES.
Yes you can call the router maker and complain but that's up to you to decide if you have the time.
I've just had my internet set up and purchased a new Modem/Router. The internet is Charter Cable 18mbps. The Modem Router combo is a Motorola Surfboard model SBG901. Once connected the internet runs fast and smooth with no problems. The only problem is when I connect each time the connection initially gained and then loses internet access for a few seconds and then slowly gains connection back. It happens on multiple computers and consistently every time. It's a secured connection and we are currently allowing only 3 MAC addresses and blocking all others. Any suggestions?