Seat Ibiza car alarm keeps going off it's a 2015

When is it going off , when left over night or what ?

Yes started just randomly last night after being parked up for about 4 hours..wouldnt turn off even when driven..then several trys turning the key in the door locks it went off..but now sounds every time the car is unlocked until key is put in ignition..any ideas would appreciate the advice thank you in advance.

Open and then shut all doors , tailgate and bonnet .If still having problems , get car battery tested as on some this can trigger the alarm especially when dropping a little over night .You say you are using the key to open , replace keyfob battery

Thank you so much will try all of the above. Much appreciated thank you.