unable to get a rep to do a simple task

I ported over my landline to a cell line, they were told not to touch my existing plan, I have a retired plan that I repeatedly told them I did not want changed under any circumstances.  That is a mobile share 3 GB plan with 3 lines, I added a separate line for unlimited Premium with 50 gb hotspot my bill on my old plan runs about 126 with only about 21 in taxes, they added the new line to my existing plan and guess what my bill went to? 219 for what they have listed as another 3gb mobile share line, 140 in line charges and yep 67 in surcharges and taxes! The frustrating part is I told them not to touch my old plan because I have been told repeatedly by att techs before that my taxes are super low on this existing plan! I have dealt with this for 2 solid days 7 different technicans, 2 trips to a local store and am mentally fried, any idea how you get to a level where someone can straighten this mess out??????!!!!!!!!!!!!!!!!!!  I was assured today when I hung up for the last time it was a completely separate line, that my other lines remained the same and NO none of that happened!!  Oh I have been dealing with the Loyalty department.