Fios business .. cant add ip blocks that have random ip addresses, lose original block?

Currently in PA, we have fios business.. we have a block of ips already, which are 5 ips and i think $20 per month.. these numbers are sequential..

We were looking into adding 10-20 more ip addresses.. the next step up according to the person i spoke to was a 13 block.. and they end up being sequential.. no way to make them random they claimed.. this 13 set is $50/m and replaces the first 5 block which i think is ridiculous.

Is there truly no way to get random ips in a block and if not, no way to retain that first block?

Our other idea was just to get a much larger block, say 50 ips and randomize from this pool, but i'm not even sure if this is an option and is probably expensive.

Thanks in advance