Simple. A lot accounts + text randomizer = unlimited DM. Because anyway you will get a ban for spam, if you use only 1 acc.
If you want to use soft. Then, you need to understand, that you need to study to use it, fix it, customize it, buy this soft, buy proxy, buy fb accounts and prepare that's all.
Maybe will be simpler, find here in bhw, who could do it for money.