Fatal error: Call to undefined function hikashop_d

Please help my google adwords campaign has gone live today and the shop has just stopped working, it worked fine last week as purchases were made - www.extendedlife.co.uk . the error message is a follows:-
Fatal error: Call to undefined function hikashop_decode() in /home/subkfork/public_html/plugins/system/hikashopaffiliate/hikashopaffiliate.php on line 247
PLEASE HELP!!!!!!!

I can't see that error on your website. It's working fine as far as I can see.
There is also no call to the hikashop_decode function in the file plugins/system/hikashopaffiliate/hikashopaffiliate.php on line 247 of the latest version of HikaShop and we don't have the problem on our end. So hard to say how you were able to get that error.
Nevertheless, a simple way to avoid it is to add the line:
if(!include_once(rtrim(JPATH_ADMINISTRATOR,DS).DS.'components'.DS.'com_hikashop'.DS.'helpers'.DS.'helper.php')) return true;

just before the line of the error.

I am not the web developer just the site owner and this is the message I get when i try to register on thee site, which is what i need to do in order to purchase and the error messaage is a hikashop message

I really need your help here if possible as web developer unavailable today and this is damaging my business

Could you confirm you have my emails please

You don't need to be a developer to copy/paste a line of text in a text file...
I already gave you the solution.

Now if you don't want to do it, simply deactivate the affiliate plugin of HikaShop via your plugin manager and wait that your web developer returns to do the change.

Nightmare - put this code in exactly as is below and got this message

Your password reset confirmation failed because the verification code was invalid. User not found

Something seriously wrong with registration and shop

Hi,

Please redownload HikaShop Business 2.1.3
Like Nicolas said the latest package (2.1.3) does not contain the "hikashop_decode" call in the line 247.
So I suppose that you do not have the latest version of this plugin.

Regards,

Hello Jerome,
In response to your message, I sent the message as a private message as I thought this the best way to make a complaint and for no other reason. The copy is NOT a pirate version and the only reason I have been trying to resolve the problem myself with limited experience of these things is because my web developer is not available to help me today. I am small business and this issue had clearly affected a full days sales. I will send your comments on to my web developer who should be able to look at them tomorrow. I will make sure the website is registered under the 'your subscription' section and will pick this up again with you tomorrow. I must say the correspondence I have received in general from both yourself and Nicolas has been somewhat obtrusive, maybe this is because you think we have not actually purchased the plug-in which I assure you I will be able to prove to the contrary tomorrow.
Katherine

Hi,

We didn't mean to be disrespectful at all. I just wanted to say that it is really easy to do the modification I was talking about.
And again, just unpublish the affiliate plugin via the plugin manager as I said and you won't have any errors related to it until your developer can review the problem.