Re seller unlimited bandwidth

Hello there, I am currently with a reseller hosting provider. I am having a query with them regarding unlimited bandwidth, they are telling me because of security reasons they cant allow me to select unlimited bandwidth for an account and instead must put 909Tb. I wish to select unlimited so it displays the infinity symbol, however, they keep giving me a new reason/excuse every time I ask them about it. Is this all true? As none of my other providers in the past wouldn't let me not have unlimited bandwidth