Unable to select different shipping method

-- url of the page with the problem -- : royalalchemist.co.uk
-- HikaShop version -- : 2.2.0
-- Joomla version -- : 3.1.1
-- PHP version -- : 5.4.17
-- Error-message(debug-mod must be tuned on) -- : Error_message
Hi
We have different shipping methods in our website if our customers don't choose any shipping, it automatically goes with Free shipping which is fine but the problem shows up when customers choose different shipping method.After they choose different shipping method and when they click on next to make payment(Using Google checkout) they get this error:
Oops!
RoyalAlchemist has sent Google a shopping cart with errors in it. We'll contact them to ask that they fix this problem. As this could be a temporary issue, you can go back in your browser to try checking out again.
Debugging information

If you are acting on behalf of the merchant, more information about this error has been made available in the Integration Console under the Tools section. You can access the details of this error directly by logging into your merchant account and then pasting the following url:
checkout.google.com/sell/ settings?section=IntegrationConsole&returnURL =https%3A%2F%2F checkout.google.com%2Fsell%2Fsettings%3Fsection%3DIntegrationConsole&serialNumber=8cce85e5-f53e-4737-832d-b330be674c85

Could you please let me know what is the problem and how can we fix it?

Many thanks

Hi,

Thanks to follow that url, connect with your account, and give us the returned error.
It will help us to see from what can the problem come. Actually we can't deduce anything.

This is what I get:

warnings:
XML we received:
<?xml version="1.0" encoding="UTF-8"?>
< checkout-shopping-cart xmlns=" checkout.google.com/schema/2 ">< shopping-cart>< items>< item>< item-name>Order #61 - 5-MeO-DALT freebase 500mg< /item-name>< item-description></item-description>< unit-price currency= "GBP">9.00000< /unit-price>< quantity>1</quantity></item><item><item-name>Order #61 - 100x 25I-NBOH Blotters HPBCD Complexed (1200ug 25I-NBOH)</item-name ><item-description ></item-description><unit-price currency="GBP">150.00000</unit-price><quantity>1</quantity></item><item><item-name>Order #61 - Shipping </item-name><item-description></item-description>< unit-price currency="">7</ unit-price><quantity>1</ quantity></item></items></shopping-cart><checkout-flow-support><merchant-checkout-flow-support/>< /checkout-flow-support></checkout-shopping-cart>
XML we sent:
< ?xml version="1.0" encoding="UTF-8"?>
< error xmlns=" checkout.google.com/schema/2 " serial-number="871f483d-c9a4-4389-941c-3ac9df1e385f" >
< error-message>Error parsing XML; message from parser is: Invalid value for attribute currency in checkout-shopping-cart/ shopping-cart/items/item/unit-price: < /error-message>
</error>

You are great nicolas..Thank you so much

It works fine but there is a new problem now. When you choose different shipping method nothing changes and you need to click next to see the change and then click next again to go to final step! As you can see this situation is very confusing because when my customers choose different shipping and click next they expect go to next step which is checkout but they dont see any changes..
I would really appreciate if you could help me
Regards