Vodacom *****ing data again

It seems that on a yearly basis my data disappears faster than you could imagine. The response from Vodacom it’s my fault when no details or settings are changed on my mobile phone. Speaking to their customer support they just state it’s my fault and I used the data. Last year my data bill was a couple of 1000’s but luckily on the one day I noticed the data disappearing at a rate of more than a gig a hour.