Arty will just stun them, the M109 has an AP value of 0 for indirect fire.

The T80U's are tough, but killable.

The Leo 2A4's are commonly used against them (according to the forums anyways), but since you can buy 16 TOW jeeps for 1 T80U (IIRC), I'd try that.

Also, part of your problem is that your tanks are sitting still. They have less chance to hit against moving tanks. The T80's will hit a stationary target with every volley, you might not.