WHY can't I find my own modem/router DOCSIS 3.1

I'm MAD.   I've been paying thru the teeth since 2014 for your routers/modems.  And simply cannot find a SINGLE modem/router DOCSIS 3.1 with telephony.  We're forced to pay for the Technicolor CGM4140COM gateway which is always acting up and buggy.   I've paid for my modems/routers 4-5x over what purchasing my own would cost.