There isnt as far as im aware,
However if you abuse it like going crazy with lots of gbs, then you will get a text asking you to slow down.
Other than that o2 policys are really good.
Need Help, Just ask. We are one big Family here in the o2 Forum.
Use iPhone XS Max dual sim, SE, Honor 10, IPad Pro 11, Apple Watch 4 LTE, 100+ Mpbs Barrier and a Record Player.