HI
good luck I am not an expert but try to put a positive spin on things when you can As you are at the start its most likely taken a lot of time to set up and get organised so would your company want to let you off as they are losing a customer at the end of the day  I would guess you will get a payment breal to sort yourself out as thats quite a common thing for most people with the way the country is at the momenr with people out of work  So cut your card up and work out what you need to get it paid off work out your Ins and Outs as best you can  and then when they contact you again you are ready to tell them exact figures and tell them that you are sorry and will not get into further difficulties again and be pro active  towards your IVA 
If they think you are going to be messing them around and doing your own things  then they maybe dont want the hassle of a customer who is not 100% commited 
Bottom line you are sorting yourself out and making the commitment to paying the debt back as best you can  the 5 years road ahead is not always smooth you have just hit a speed bump early on 
Stay positive and remember that your IVA is just that Individual to you  No matter what other peoples issues are they all have pros and cons and I am sure that your company can give you some leeway to allow you to continue  The more they can get to the end the better for them 
Easy to say dont worry and everything will be fine when its somebody else Just take care of yourself ok You are dealing with this as best you can and you will come out the other side stronger for it 
I am also trying to convince myself with this gibberish at the same time 

)  I know what its like at the start and to get the IVA started is pretty stressful and sleepless nights  but you wull make it