Can anyone give me a explanation of this sentence from my 2級 grammar book?

電気代に加えて、ガス代までが値上がりした

I'm not familiar with までが

"In addition to the electricity bill, the gas bill increased in price"

is my stab at it. But if that's right, why not just が？

I don't think the までが　is anything special.
電気代に加えて、ガス代まで In addition to the electricity bill, even the gas bill...
I think it's just two particles that ended up next to each other.

oh ok, that makes sense. Thanks!