Sorry for the late update.
To resolve the payment errors I had to edit /plugins/hikashoppayment/authorize/authorize.php
Line 245 - CHanged TRUE & FALSE under has tax to YES & NO
$tax+=$product->order_product_quantity*round($product->order_product_tax,(int)$this->currency->currency_locale['int_frac_digits']);
$has_tax = 'YES';
}else{
$has_tax = 'NO';
The item name was missing on the payment page to resolve I had to duplicate order_product_name to pass to Payeezy.
Line 255:
$vars["x_line_item"][]=substr($product->order_product_code,0,30).'<|>'.substr(strip_tags($product->order_product_name),0,30).'<|>'.substr(strip_tags($product->order_product_name),0,30).'<|>'.$product->order_product_quantity.'<|>'.round($product->order_product_price,(int)$this->currency->currency_locale['int_frac_digits']).'<|>'.$has_tax;