Samsung galaxy s4 ussd code running message appears upon phoning and prevents access to keypad

[liz dorman]

I am new to the galaxy s4, only had it for the last few hours! and today whilst checking my balance (*174#) the USSD code running appeared and now keeps appearing everytime I make a phonecall and as a result whilst on the phone I cant access the dial pad as this USSD code running message appears and prevents me from using the phone, so I cant hang up etc during/after a phonecall as a result and so its so frustrating as Ive no idea what to do, any help would be much appreciated! I really do not want to have to reboot phone as just have all my contacts, photos etc set up on it! thankk you for helping! great forum! Lizzy