Today, UA credited my credit back 6x$5.6 which I assume for my original two bookings. However only charged me 3x$5.6 which is only one booking that the second agent created. All my 3 current reservations are confirmed and ticketed. Should I worry about my bookings?

Hello, originally I booked two flight from LAX to LIH (9100 miles/person) and from OGG to LAX(9100 miles/person) on 3/31. yesterday I realized I could have a free leg from LIH to OGG if I book multicity. I called UA and asking if the agent can combine my two bookings and throw in the free trip from LIH to OGG. He said he can do it. I received ticketing email from LIH to OGG while I was on the phone with him. I thought he was able to add the free leg. However I looked my account and I noticed my two original booking are gone and the agent just hang up on me when I said that. I called back and another agent helped me to put back my two original booking, however, she said no redeye flight from OGG to LAX, I checked my self and I can see the reward flight and she just told that she has more real time but she changed the flight time. original flight was a redeye flight and has much less miles and that is why I booked it. The flight she changed was 25k miles/person. That flight was immediately ticketed while I was on the phone with her and one the email receipt, I did not see miles taken. I asked her at least two times that the 3 bookings (I do not know why she can not combine the trip in one) will charge my original miles and she confirmed. Today I received ticketing information from LAX to LIH, I was charged 11600/person. I am still waiting for ticketing for LIH to OGG. Now I am worried about what will happen to UA charge my miles. Anyone has any experience to share? I just do not want to have a few days before my trip and they cancel my tickets or even worse we are at the airport and were told our flight are cancelled. I heard horrible stories before and I just want to prevent this happen. I would like to call them again and I think the agent are not very knowledgeable yesterday. Should I call any particular department can sort this out? Thank you very much any input are appreciated.