HUAWEI ASCEND MATE 7 Version MT7-J1

Good morning I want to make an inquiry and see if someone can help me, buy this fabulous smarphone Huawei Ascend Mate 7 model MT7-J1, I live in Cordoba Argentina Huawei it works perfect but I have a problem ...... When you use mode Automatic preferred network (4G / 3G / 2G) leaves me not receive calls, or if I call (DISCAN) continuously given as busy, as if I were on a call, I myself make a call from another phone to my number in Huawei and not receiving my call ...... da busy line, also when I want to make a call from my first attempt Huawei terminates the call, the second attempt disappears from the notification bar 4G and only then performs the call went to my provider of Movistar service to see if my problem was SimCard, tried to take it off the other smarphone and works perfect, or is it a problem in my smarphone, I call us the attention that selecting the option .. ...... Automatic Preferred network mode (3G / 2G) ..... the problem goes away ,,,, in this way can receive and make calls perfectly, the fact is you buy this model MT7-J1 because it is the only model in this line that supports the band 4 (B4) used in Argentina to use the 4G / LTE and although all of 4G works more perfect in this smarphone I only have this problem with the calls,
If anyone can help me and know how to solve this problem really appreciate it, send mail to HUAWEI but never answered me, that's what I do not understand, because HUAWEI offers its website, if when customers have a problem never respond or offer help and here in Argentina HUAWEI service ...... not a rock, I hope you can help me thank you very much from now ........ ADRIAN from Cordoba Argentina.